This invention relates generally to controls, and more particularly to a foot pedal control coupled to a fuel dispensing system of an internal-combustion engine.
Actuation of a foot pedal coupled to a fuel dispensing system of an engine alters the output of fuel discharged by the fuel dispensing system. Conventionally, the unactuated foot pedal is held in a home or idle position by a spring arrangement, and the operator, by depressing the pedal causes an increase of the fuel output from the fuel dispensing system, thereby increasing engine RPM and/or power output of the engine.
An important feature of diesel engines as well as many spark-ignition engines is the fuel-injection system, consisting of pumps that meter and place the fuel under injection pressure, the injection nozzles and the governing controls. Controlling the rate of fuel dispensed to the cylinders of an internal combustion engine, commonly referred to as throttle control, is accomplished in a fuel-injection system by adjusting the output of a fuel pump or a system of fuel pumps that supply the cylinders. Fuel controls have evolved from mechanical linkages coupling a foot pedal to a control rack of a fuel pump system, to an electronic linkage coupling the foot pedal to a computer, the computer monitoring, inter alia, a sensor that detects incremental movement of the foot pedal, and responsive to such detected movement and other input data, controlling the output of the fuel pump system.
Many modern internal-combustion engines are computer controlled. For example, a fuel pump system is suitably operated by one or more servomechanisms responsive to control signals from a computer, which monitors an input signal provided by a sensor coupled to the foot pedal. The foot-pedal sensor, suitably a potentiometer, is actuated in response to depression of the foot pedal by the operator of the vehicle. The computer thus controls fuel flow to the engine, generating appropriate control signals in response to monitored input signals from the foot-pedal potentiometer as well as other input signals from sensors which detect both internal and external engine operating parameters such as temperature, humidity, barometric pressure, engine RPM and load, etc., providing increased engine efficiency, fuel economy and reduced emission of pollutants to the atmosphere.
An early design of an electronic control system located the movement detecting sensor in the engine compartment near the fuel pump; however, this arrangement proved undesirable due to the complex mechanical linkage required to connect the foot pedal to the sensor. Moreover, the harsh operating environment of the engine compartment exposed the sensor to heat, oil and dirt, which can contribute to premature failure of sensitive components. Subsequent designs thus located the sensor in the cab or operator compartment, the sensor being incorporated in a foot pedal arrangement that included a means for providing rotative motion of a potentiometer in response to depression of the foot pedal. A foot pedal, its support structure, sensors such as a potentiometer and the various interconnecting components are collectively 10 referred to herein as a "foot pedal arrangement". One such implementation shown in U.S. Pat. No. 4,958,607, which is assigned to the same assignee as the instant invention, provides a suspended pedal configuration, which is a desirable arrangement; however, many of the mechanical elements are disposed exteriorly on the support structure, and the pivot of the foot pedal is spaced apart from the front wall farther than desirable in the limited space of the truck cab. Particularly, the foot-pedal pivot is situated relatively far from the front wall of truck cab, well beyond the pivot of the potentiometer actuating mechanism. It is desirable to locate the pivot point of the foot pedal as close to the front wall as possible in order to conserve space in the often cramped confines of a truck cab. Further, in the '607 arrangement, torque was applied by coil springs to the shaft that actuated the potentiometer, consequently the coil springs were required to rotate through the same arc as the potentiometer shaft, resulting in a pedal pressure differential from idle to full throttle that was higher than desirable for optimum operator comfort.
It is therefore a principal object of the present invention to provide a improved foot pedal arrangement.
A more specific object of the present invention is to provide a foot pedal arrangement with improved pedal pressure differential.
Another object of the instant invention is to provide an improved foot pedal arrangement which locates the pivot of the foot pedal close to the front wall of the truck cab.
It is another object of the present invention to provide an improved foot pedal arrangement requiring reduced force to hold the pedal actuated, thereby increasing operator comfort.
Another object of the invention is to provide an improved compact foot pedal arrangement with an aesthetically pleasing, uncluttered appearance, and having fewer moving components virtually all of which are internally disposed for safer operation and for protection from dirt and contaminants.